The embodiment of the invention provides an energy-saving transformer. The transformer comprises an iron core, a low voltage winding and a high voltage winding; for any phase of the energy saving transformer, the low voltage winding is formed by connecting at least two low voltage sub-windings in series, and the high voltage winding is formed by connecting at least two high voltage sub-windings inseries; the low voltage sub-windings and the high voltage sub-windings are concentrically arranged around an iron core and arranged staggerly. Accordingly, by making the low voltage sub-windings andthe high voltage sub-windings which are concentrically arranged around the iron core and arranged staggerly connected in series separately to form the low voltage winding and the high voltage windingrespectively, amplitude leakage magnetic set pairs are increased, and the micro reactive power loss in normal operation of the transformer can be achieved, and meanwhile the voltage adjustment rate isimproved; the structure is simple, and the manufacturing process is reasonable.